reparse_windows.go

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package windows
     6  
     7  import (
     8  	"syscall"
     9  	"unsafe"
    10  )
    11  
    12  const (
    13  	FSCTL_SET_REPARSE_POINT    = 0x000900A4
    14  	IO_REPARSE_TAG_MOUNT_POINT = 0xA0000003
    15  
    16  	SYMLINK_FLAG_RELATIVE = 1
    17  )
    18  
    19  // These structures are described
    20  // in https://msdn.microsoft.com/en-us/library/cc232007.aspx
    21  // and https://msdn.microsoft.com/en-us/library/cc232006.aspx.
    22  
    23  type REPARSE_DATA_BUFFER struct {
    24  	ReparseTag        uint32
    25  	ReparseDataLength uint16
    26  	Reserved          uint16
    27  	DUMMYUNIONNAME    byte
    28  }
    29  
    30  // REPARSE_DATA_BUFFER_HEADER is a common part of REPARSE_DATA_BUFFER structure.
    31  type REPARSE_DATA_BUFFER_HEADER struct {
    32  	ReparseTag uint32
    33  	// The size, in bytes, of the reparse data that follows
    34  	// the common portion of the REPARSE_DATA_BUFFER element.
    35  	// This value is the length of the data starting at the
    36  	// SubstituteNameOffset field.
    37  	ReparseDataLength uint16
    38  	Reserved          uint16
    39  }
    40  
    41  type SymbolicLinkReparseBuffer struct {
    42  	// The integer that contains the offset, in bytes,
    43  	// of the substitute name string in the PathBuffer array,
    44  	// computed as an offset from byte 0 of PathBuffer. Note that
    45  	// this offset must be divided by 2 to get the array index.
    46  	SubstituteNameOffset uint16
    47  	// The integer that contains the length, in bytes, of the
    48  	// substitute name string. If this string is null-terminated,
    49  	// SubstituteNameLength does not include the Unicode null character.
    50  	SubstituteNameLength uint16
    51  	// PrintNameOffset is similar to SubstituteNameOffset.
    52  	PrintNameOffset uint16
    53  	// PrintNameLength is similar to SubstituteNameLength.
    54  	PrintNameLength uint16
    55  	// Flags specifies whether the substitute name is a full path name or
    56  	// a path name relative to the directory containing the symbolic link.
    57  	Flags      uint32
    58  	PathBuffer [1]uint16
    59  }
    60  
    61  // Path returns path stored in rb.
    62  func (rb *SymbolicLinkReparseBuffer) Path() string {
    63  	n1 := rb.SubstituteNameOffset / 2
    64  	n2 := (rb.SubstituteNameOffset + rb.SubstituteNameLength) / 2
    65  	return syscall.UTF16ToString((*[0xffff]uint16)(unsafe.Pointer(&rb.PathBuffer[0]))[n1:n2:n2])
    66  }
    67  
    68  type MountPointReparseBuffer struct {
    69  	// The integer that contains the offset, in bytes,
    70  	// of the substitute name string in the PathBuffer array,
    71  	// computed as an offset from byte 0 of PathBuffer. Note that
    72  	// this offset must be divided by 2 to get the array index.
    73  	SubstituteNameOffset uint16
    74  	// The integer that contains the length, in bytes, of the
    75  	// substitute name string. If this string is null-terminated,
    76  	// SubstituteNameLength does not include the Unicode null character.
    77  	SubstituteNameLength uint16
    78  	// PrintNameOffset is similar to SubstituteNameOffset.
    79  	PrintNameOffset uint16
    80  	// PrintNameLength is similar to SubstituteNameLength.
    81  	PrintNameLength uint16
    82  	PathBuffer      [1]uint16
    83  }
    84  
    85  // Path returns path stored in rb.
    86  func (rb *MountPointReparseBuffer) Path() string {
    87  	n1 := rb.SubstituteNameOffset / 2
    88  	n2 := (rb.SubstituteNameOffset + rb.SubstituteNameLength) / 2
    89  	return syscall.UTF16ToString((*[0xffff]uint16)(unsafe.Pointer(&rb.PathBuffer[0]))[n1:n2:n2])
    90  }
    91
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